Protective eyewear are typically utilized in a work related environment in which flying objects or projectiles may be present. An example of such a work environment is carpentry in which the use of a power saw may cause wood splinters to spray away from the cutting area. In order to protect the eyes, a front lens assembly is usually worn, whether or not the user requires corrective lenses. Also, side shields are provided on or adjacent the temple arms of the eyewear to prevent objects from striking the eyes frown the side.
Weight is typically a deterrent to the wearing of the eyewear. Thus, it is preferred that the eyewear be lightweight and comfortable so as to encourage its use. Many protective eyewear that are presently available utilize plastic lenses and frame members and are lightweight. These eyewear also include the desired comfort elements of regular glasses.
Because of the use of plastic for the lens and/or the side shields for the eyewear, the materials tend to be abraded during normal use. Lightweight objects moving across the lens surface may cause scratches therein which affect the clarity of the lens. Additionally, placement of the lens in a pocket, tool chest or the like may cause further scratching. In this regard, it may be preferable that the lens be replaceable.
Another feature that may be applied to eyewear is the use of color shading on the lens. The lens may include an amber or yellow coloring for increased visibility, or other coatings as desired. In certain situations, a replaceable lens assembly may be appropriate so that different shadings can be used on the same pair of eyewear.
In order to be classified as protective eyewear, the eyewear must meet certain standards. These standards apply to impact resistance, burning rate and replacement of the lens. In addition, certain test methods are identified within these standards. The standards for Canada are set by the Canadian Standards Association (CSA) and are generally defined in CSA Z94.3-92. In the United States, the American National Standard Institute (ANSI) has set standards under the designation Z87.1-1989.